The Zongwulong Shan-Qinghai Nanshan tectonic belt of the northern Tibet Plateau experienced a protracted tectonic history, including the openings and closures of the Proto- and Paleo-Tethyan Oceans. Although the tectonic belt has been extensively studied, details regarding the tectonic processes involved in its development remain controversial. To better constrain the tectonic processes of this tectonic belt, we conducted detailed field geological mapping, zircon U-Pb geochronology, and whole-rock geochemical and Sr-Nd isotopic analyses. Our results show that intrusive rocks in the tectonic belt crystallized in ca. 292–233 Ma, perhaps in an arc/subduction setting. Geochemical and Sr-Nd isotopic data suggest that Early Permian–Late Triassic ultramafic-intermediate intrusions were sourced from the enriched mantle, whereas intermediate-acidic rocks were sourced from mixed crust-mantle. We present the tectonic model that involves: (1) Early Devonian–Early Permian intracontinental extension occurred in the northern margin of the Qaidam continent (ca. 416–292 Ma); (2) Early Permian–Late Triassic northward subduction of the Paleo-Tethyan Ocean resulted in arc magmatism (ca. 292–233 Ma); and (3) subsequent Late Triassic intracontinental extension (ca. 233–215 Ma). Our results suggest that the Late Paleozoic–Early Mesozoic development of the Zongwulong Shan-Qinghai Nanshan was related to the opening, subduction, and slab retreat of the Paleo-Tethyan Ocean, which has key implications for the tectonic evolution of the northern Tibetan Plateau.

The Altyn Tagh fault zone (ATFZ), which defines the northern boundary of the Tibetan Plateau, is one of the most striking features related to the India/Eurasia collision. Concurrent with the strike-slip movement, vertical uplift, and topographic building have formed a ~3 000–4 000 m height difference between the Tarim Basin (TB) in the north and the Tibetan Plateau in the south. However, the spatial uplift characteristics and mechanism have not been well understood, particularly in the Late Quaternary. This research presents a comprehensive geomorphic analysis to establish the Late Quaternary tectonic uplift pattern for the entire ATFZ. We statistically excluded climatic and lithological factors that provided prominence for tectonism; combined with leveling data, river incision rate, and seismicity data, we reveal the along-strike and across-fault vertical deformation variations. The spatial distribution of the integrated geomorphic index (IGI) suggests significant differences between the two sides of the ATFZ. The IGI values decrease with slip rates in the northwestern side of the ATF, whereas wave-like in the southeastern side. The significant along-strike deformation difference between the two sides of the ATFZ may cause by differential rheology. These findings are crucial for assessing regional seismic hazards and providing new independent data to understand the Late Quaternary deformation style of the northern boundary of the Tibetan Plateau.

A set of ultramafic-mafic-felsic rock assemblages was discovered in the Longshenggeng area of the eastern part of the East Kunlun orogenic belt. Petrography, chronology and whole-rock geochemistry were conducted on this set of intrusive rock assemblages. U-Pb dating of apatite shows that the lherzolite formed at 492 ± 5 Ma, the granite at 473 ± 6 Ma, and the diabase at 260 ± 14 Ma, respectively. The lherzolites belong to a supra-subduction zone type (SSZ-type) ophiolite component above a subduction zone; the granites formed in an ocean-continent subduction setting; and the diabases represent products of partial melting of an asthenospheric mantle at shallow depth. The East Kunlun orogenic belt features the East Kunzhong and Buqingshan-Animaqing ophiolitic mélange belts, with the latter representing remnants of the Proto-Tethys Ocean. The Late Cambrian lherzolites and granites in the Longshenggeng area were magmatic products of the back-arc ocean basin and island arc formed during the northward subduction of the Proto-Tethys Ocean. Subsequently, extensive island arc magmatism occurred from the Late Permian to Middle Triassic, driven by the northward subduction of the Paleo-Tethys Ocean beneath the East Kunlun Block. The diabase may have formed during the transition from subduction to post-collisional extension.

The Metal Stable Isotope Geochemistry Laboratory (MSIGL) at the University of Science and Technology of China has developed state-of-the-art analytical methods for twelve stable isotope systems, including Mg, Si, V, Fe, Cu, Zn, Rb, Sr, Ag, Cd, Ba, and U. Geological and biological samples were first digested by acid dissolution or alkali dissolution. The target element was subsequently purified by the column chromatography method. A Neptune Plus MC-ICP-MS was used to measure isotope compositions and the isotope bias caused during measurements was calibrated by standard bracketing and/or the double spike method. The analytical procedure was carefully checked to ensure the high precision and accuracy of the data. Here, we summarized the protocol of these established methods and compiled the standard data measured at our lab as well as those reported in literature. This comprehensive dataset can serve as a reliable benchmark for calibration, method validation, and quality assurance in metal stable isotope analyses.

The Yangtze River, with a length of approximately 6 300 km, holds the distinction of being the largest river in East Asia that empties into the Pacific Ocean. Its formation is intricately linked to regional tectonic activity and climate fluctuations. However, the exact timeline for the formation of the Yangtze River remains elusive. This study investigates the provenance of the Late Cenozoic strata in the Wangjiang Basin, situated in the Lower Yangtze River, through the application of detrital zircon U-Pb dating. Seven sand samples were analyzed, leading to the identification of new U-Pb detrital zircon ages (n = 577). Our study reveals that the sand materials found in the Pliocene gravel beds of the Anqing Formation originate predominantly from the Yangtze River. The findings of our study, along with the provenance tracing of boreholes in the Yangtze River Basin and the shelf sea in East China, provide compelling evidence for the continuous presence of the Yangtze River throughout the Pliocene period. The development of the Yangtze River during the Pliocene is intricately connected to both the tectonic adjustments occurring at the southeastern margin of the Tibetan Plateau and the intensification of the Asian Monsoon.

The Xing'an-Inner Mongolia Orogen is a critical tectonic unit for constraining the evolution of the Paleo-Asian Ocean. However, the location and time of the closure of the Paleo-Asian Ocean are still debated. Here, we select a representative basin in Dashizhai in northeastern China, using U-Pb zircon geochronology and geochemistry to analyze the sedimentary facies, depositional ages, and provenance. The results show that the ages of the Dashizhai Formation range from 400 to 347 Ma, the Shoushangou Formation range from 400 to 348 Ma, the Zhesi Formation range from 307 to 252 Ma, and the Linxi Formation range from 299 to 241 Ma. The Dashizhai Formation is composed of metamorphic andesite and clastic rocks. The Shoushangou Formation comprises siltstone, rhyolite, and argillaceous siltstone. The Zhesi and Linxi Formations are composed of mudstone and argillaceous siltstone. Geochemical data shows that these rocks are enriched in light rare earth elements and depleted in Eu with various La/Sc, Th/Sc, and La/Co ratios. The Permian Dashizhai Basin is from Permian volcanic and felsic igneous rocks from the Ergun, Xing'an, and Songliao blocks. The absence of the Late Carboniferous strata in the Dashizhai Basin indicates an extension setting during this period. Furthermore, we suggest the Xing'an-Inner Mongolia Orogen was an uplifting process associated with evolution the Paleo-Asian Ocean during the Late Permian.

The Central Yunnan Basin (CYB) that tectonically located on the southwest margin of the Yangtze Block and to the eastern segment of the Paleo-Tethys tectonic domain, is a typical 'red bed' sedimentary basin formed since Late Triassic. The CYB is composed of mega-thick fluvial and lacustrine facies successions. However, the tectonic evolution and sedimentary provenance studies on this basin are scarce. In this study, we report new detrital zircon ages of four sandstones from the Lower Jurassic Fengjiahe Formation (FJF), including four major clusters of 2 060–1 810, 870–760, 485–430, and 280–254 Ma, with sporadic Archean, Cambrian, and Triassic ages. We interpret that the Archaean and Proterozoic zircons were mainly derived from the western Yangtze Block, which may recycle from the Jiangnan Orogen, the Cathaysia Block and the Proterozoic igneous rocks. Ordovician and Silurian zircons were probably from the Ailaoshan orogenic belt, and the Lancang Group in western Yunnan, as well as the Yangtze, Cathaysia and Indosinian blocks. Permian zircons probably came from the Ailaoshan orogenic belt and the Emeishan basalt. The youngest zircon age of ~212.9 Ma indicates that the depositional age of the FJF is younger than the Norian stage. We also proposed a geodynamic model of the CYB and the Ailaoshan orogenic belt during the Mesozoic. The Simao Block to the west of the CYB constituted the Ailaoshan orogenic belt and collaged with the Yangtze Block during the Early Triassic, provided sedimentary provenance to the CYB. The Changning-Menglian zone that composed of the Baoshan and the Simao Blocks, uplifted in the Late Triassic and provided provenance to the CYB. Collapse of the Ailaoshan orogenic belt in Late Triassic probably provided channel for source materials that transported from the Lincang granites to the CYB. We propose a transtensional tectonic setting of the central Yunnan during the Early Jurassic, after a short collision during the Indosinian Movement in the Late Triassic.

The giant Jiama deposit is a post-collisional porphyry Cu-polymetallic system located in the Gangdese metallogenic belt of Tibet. It consists of three deposits: The Main deposit, the Zegulangbei deposit, and the South Pit deposit according to exploration and research. The South Pit deposit is a high-grade Cu-Pb-Zn deposit, but its genesis is unclear. To investigate its genesis, a detailed study was conducted on the deposit geology, geochronology and amphibole geochemistry. The results indicate that the weighted average ²⁰⁶Pb/²³⁸U age of the zircons from the granite porphyry in the South Pit is 15.38 ± 0.45 Ma, and the molybdenite from the mineralized skarn yield a Re-Os isochron age of 15.23 ± 0.22 Ma, in line with the age of the Main deposit (15.7–14.3 Ma). The amphiboles in the granite porphyry of the South Pit, magnesiohornblende and actinolite, are high in Mg and Ca and low in K. They crystallized at temperatures of 705–749 ℃, pressures of 0.44–0.67 kbar, oxygen fugacity of -14.31– -13.69 (NNO), and depths of 1.7–2.5 km. Mapping of structure and alteration indicates that the South Pit skarn developed due to the metasomatism of marble of hornfels or carbonate in fold hinge dilation and an interlayer detachment zone by magmatic hydrothermal fluids. According to the age of magmatism and geological features, the South Pit deposit and the Main deposit have originated from the same Miocene magmatism, but the South Pit deposit was affected by the gliding nappe tectonic system. The amphibole geochemistry indicates that the ore-related magma of the South Pit has a high oxygen fugacity and is rich in water.

Quartz trace elements are extensively employed in studying magmatic evolution, fluid evolution, and metal enrichment. The Bianjiadayuan Ag-Pb-Zn-Sn deposit is a typical magmatic-hydrothermal system in northeastern China, however, studies on its complex magmatic-hydrothermal evolution are limited. This study investigates the quartz from the Bianjiadayuan deposit to gain insight into the physicochemical evolution of mineralization using cathodoluminescence (CL) textures and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of quartz. Five types quartz (Q1 to Q5) were identified. From Q1 in quartz porphyry to Q5 in Ag-Pb-Zn veins, the CL intensity and Ti content gradually decreases, and Ge, Ge/Ti, and Al/Ti ratios increase, indicating a temperature decline from magmatic to hydrothermal stages. The Sb content shows an opposite trend to Ti content, correlating positively with Ge content in quartz, suggesting that Sb content could also be temperature-dependent. These trace elements in quartz indicate cooling is critical for Ag mineralization. Furthermore, quartz phenocryst (Q1) from the quartz porphyry shows low Al/Ti (mostly < 4) and Ge/Ti ratios (< 0.04), suggesting a low degree of magmatic evolution. The Sb content in Q5 from Ag-Pb-Zn-quartz veins (> 1 ppm, mostly tens of ppm) is notably higher compared to quartz in other lithologies including Sn-bearing quartz veins (< 1 ppm), suggesting that Sb contents can serve as an effective indicator of Ag mineralization.

The Raohe area of Heilongjiang Province, Northeast China belongs to the Nadanhada Terrane, which was in low latitudes of Panthalassa during the Triassic. The composition of the Late Triassic conodont fauna, derived from limestone lenses interpreted to formed on seamounts, provides important new information on the pelagic biota in this ocean. New conodont samples collected from sections at Minzhu, Minnan and Chigangbei sections belong to three Norian conodont zones. In ascending order, they are: Mockina postera Zone, Mockina bidentata Zone and Parvigondolella andrusovi Zone. The Norian conodont fauna in the Raohe area has distinct attributes: there are a lot of cosmopolitan species (e.g., Mockina postera, Mockina bidentata, Parvigondolella andrusovi) which enable good global correlation; endemic conodont species are also present (e.g., Mockina sakurae, Mockina shamiseni, Norigondolella nadanhadaensis) indicating that Panthalassa Ocean conodont populations also contained unique taxa; and some conodonts belong to taxa with much shorter ranges in surrounding epeiric seas (e.g., Carnepigondolella pseudoechinata, Neocavitella cavitata and Epigondolella vialovi). The presence of the latter “relicts” indicates that the seamounts were persistently suitable habitats for many millions of years in the Late Triassic.

Occurrence and abundance of molecular hydrogen in natural geologic reservoirs are enigmatic, due to its various sources, diverse migration pathways and complicated biological and chemical reactions. Natural gas samples containing hydrogen from producing wells in several sedimentary basins in China were collected in this study, and gas abundances and isotopic compositions of these gases were compared with those in global petroliferous basins and deep intrusive rocks. Several geochemical indicators were suggested for identifying sources, migration and accumulation mechanisms of hydrogen in the subsurface environment. Hydrogen contents in natural gas deposits have contributions from various sources with the following high-to-low order: microbial degradation > serpentinization > deep mantle volatile release > radiation-induced water decomposition > thermal cracking of organic matter. A hydrogen-rich reservoir in Kansas, USA, is specifically analyzed to determine its formation mechanism. This study suggests that future exploration of geological hydrogen resources may focus on the igneous rock bodies with overlying dense sedimentary rocks in the continental rift systems.

For an improved understanding of gas enrichment mechanism in the eastern Sichuan Basin, South China, twelve natural gas samples were obtained from carbonate reservoirs of the Upper Permian strata to analyze the hydrocarbon and non-hydrocarbon gas compositions, stable carbon and hydrogen isotopes ratios of hydrocarbons, and noble gas isotope ratios. The gas samples in the Upper Permian reservoirs principally consist of alkane gas with a dryness ratio ranging from 127.9 to 1 564.4. The carbon isotope ratio of methane (δ¹³C₁) was almost constant at -34.1 to -31.3‰, but the carbon isotope ratio of ethane (δ¹³C₂) varied from -36.6‰ to -25.8‰. The hydrogen isotope ratio of methane (δ²HC₁) also displayed a wide range from -137‰ to -127‰. The large variations in the dryness ratio, δ¹³C₂, and δ²HC₁ with almost constant δ¹³C₁ suggest the mixing of sapropelic and humic origins for hydrocarbon gases in these reservoirs. A high concentration of hydrogen sulfide (H₂S) originated from the thermochemical sulfate reduction (TSR), which was positively correlated with δ¹³C₁ (or δ¹³C₂) in individual gas fields. TSR altered δ¹³C₁ (or δ¹³C₂) and resulted in the abnormal character of isotopic reversal in the individual samples. The δ¹³C₁ (or δ¹³C₂) in most gas samples, independent of H₂S concentration, further displayed reversed carbon isotopes because of the mixture of thermogenic gases with various thermal maturity levels. The measured argon isotope ratio (⁴⁰Ar/³⁶Ar) varied from 310 to 1 225, which suggests that the oldest 320 Ma source rock age corresponds to Permian shales. The analysis of the gas origin and the identification of primary source rock have made a significant contribution to further understanding the resource potential and distribution of natural gas in the Upper Permian, and have great implications for gas exploration in the eastern Sichuan Basin.

The Yingshan Formation of the Lower–Middle Ordovician in the Tarim Basin (NW China) was mainly deposited in a shallow platform, which was intensely bioturbated with burrows filled with both dolomites and calcites. This study aims to figure out the controls on the dolomitization of burrow infills and the effects on petroleum reservoir quality based on petrographic examination, fluid inclusion microthermometry, and isotopic (C-O-Sr) geochemical analyses. The differentiation of burrow-associated carbonates (dolomites and calcites) was likely controlled by the interactions of sea-level oscillations of variable orders and depositional environments. The burrow-associated dolomites (BADs) were precipitated in a relatively restricted (i.e., lagoon) depositional environment during the lowstand of long-term sea level. In contrast, the burrow-associated calcites (BACs) were formed in a water circulation-improved lagoonal environment during the transgression of long-term sea level. Isotopic geochemical data indicate that the BADs in the Yingshan Formation were formed from slightly saline (i.e., mesosaline to penesaline) seawater, whereas the BACs were precipitated from nearly normal seawater. In addition to the anoxic condition, the presence of marine-sourced organic matter and sulfate-reducing bacteria, and a sufficient supply of dolomitizing fluids enriched in magnesium ions (Mg²⁺) and their Mg²⁺ concentration may have played a critical role in the formation of BADs. In the more permeable and disturbed burrow sediments as a result of burrowing, penetrating fluids with higher salinities and higher Mg²⁺ concentration relative to seawater favored dolomite precipitation. The fluids with seawater-like Mg²⁺ concentration, however, would lead to calcite precipitation. The progressive dolomitization of these burrowed sediments could have propagated the dolomitizing fronts and extended into ambient limestones, leading to the development of extensive dolomites. This dolomitization process can improve the petrophysical properties (porosity and permeability) and the potential as hydrocarbon reservoirs during the emplacement of hydrocarbons from underlying source rocks of the Cambrian to Lower Ordovician.

The connectivity of shale pores and the occurrence of movable oil in shales have long been the focus of research. In this study, samples from wells BX7 and BYY2 in the Eq3⁴-10 cyclothem of Qianjiang Formation in the Qianjiang depression, were analyzed. A double mercury injection method was used to distinguish between invalid and effective connected pores. The pore characteristics for occurrence of retained hydrocarbons and movable shale oil were identified by comparing pore changes in low temperature nitrogen adsorption and high pressure mercury injection experiments before and after extraction and the change in the mercury injection amounts in the pores between two separate mercury injections. The results show that less than 50% of the total connected pores in the Eq3⁴-10 cyclothem samples are effective. The development of effective connected pores affects the mobility of shale oil but varies with different lithofacies. The main factor limiting shale oil mobility in Well BX7 is the presence of pores with throat sizes less than 15 nm. In Well BYY2, residual mercury in injection testing of lamellar dolomitic mudstone facies was mainly concentrated in pores with throats of 10–200 nm, and in bulk argillaceous dolomite facies, it was mainly concentrated at 60–300 nm. The throats of hydrocarbon-retaining pores can be 5 nm or even smaller, but pores with movable shale oil in the well were found to have throat sizes greater than 40 nm. Excluding the influence of differences in wettability, the movability of shale oil is mainly affected by differences in lithofacies, the degree of pore deformation caused by diagenesis, the complexity of pore structures, and the connectivity of pore throats. Dissolution and reprecipitation of halite also inhibit the mobility of shale oil.

On January 7, 2025, an Ms6.8 earthquake struck Dingri County, Xigazê City, in the Xizang Autonomous Region. The epicenter, located near the Shenzha-Dingjie fault zone at the boundary between the Qinghai-Xizang Plateau and the Indian Plate, marked the largest earthquake in the region in recent years. The Shenzha-Dingjie fault zone, situated at the boundary between the Qinghai-Xizang Plateau and the Indian Plate, is a key tectonic feature in the India-Eurasia collision process, exhibiting both thrust and strike-slip faulting. This study analyzed the disaster characteristics induced by the earthquake using Differential Synthetic Aperture Radar Interferometry (D-InSAR) to process Sentinel-1 satellite data and derive pre- and post-earthquake surface deformation information. Additionally, high-resolution optical remote sensing data, UAV (unmanned aerial vehicle) imagery, and airborne LiDAR (light detection and ranging) data were employed to analyze the spatial distribution of the surface rupture zone, with field investigations validating the findings. Key results include: (1) Field verification confirmed that potential landslide hazard points identified via optical image interpretation did not exhibit secondary landslide activity; (2) D-InSAR revealed the co-seismic surface deformation pattern, providing detailed deformation information for the Dingri region; (3) Integration of LiDAR and optical imagery further refined and validated surface rupture characteristics identified by optical-InSAR, indicating a predominantly north-south rupture zone. Additionally, surface fracture features extending in a near east-west direction were observed on the southeast side of the epicenter, accompanied by some infrastructure damage; (4) Surface fracture was most severe in high-intensity seismic areas near the epicenter, with the maximum surface displacement approximately 28 km from the epicenter. The earthquake-induced surface deformation zone spanned approximately 6 km by 46 km, with deformation concentrated primarily on the western side of the Dingmucuo Fault, where maximum subsidence of 0.65 m was detected. On the eastern side, uplift was dominant, reaching a maximum of 0.75 m. This earthquake poses significant threats to local communities and infrastructure, underscoring the urgent need for continued monitoring in affected areas. The findings highlight the effectiveness of multi-source data fusion (space-air-ground based observation) in seismic disaster assessment, offering a methodological framework for rapid post-earthquake disaster response. providing a valuable scientific foundation for mitigating secondary disasters in the region.

Ground response analysis and determination of site-specific ground motion parameters are necessary for evaluating seismic loads to enable sustainable design of aboveground and underground structures, particularly in deep overburden sites. This study investigates the influence of bedrock interface conditions and depth of soil deposits on obtained site-specific ground motion parameters. Employing the one-dimensional seismic response analysis program SOILQUAKE, the ground responses of five representative soil profiles and 1 050 case studies are calculated considering three different site models of seismic input interfaces. The analysis employs the actual bedrock interface with a shear wave velocity of 760 m/s as the reference input bedrock interface. The results illustrate that the selection of the bedrock interface condition significantly affects the seismic response on the ground surface of deep overburden sites. Specifically, the ground surface acceleration response spectra at longer periods are notably smaller compared to those at the actual bedrock site. This may present a challenge for designing long-period high-rise buildings situated in deep overburden sites. It is recommended to select a seismic input bedrock interface closely approximating the actual bedrock depth when conducting seismic response analyses for deep overburden sites.

The mechanism involved in deep-seated landslide-debris flow disaster chains has been studied for many years, however, it is still not completely understood. This study aims to analyze the key factors that were involved and led to the geological disaster of Shaziba 62.0 m deep landslide-debris flow. Two extensive field investigations were conducted before and after the slope failure event. The study further used drilled cores, high-density resistivity method, and aerial photographs to obtain valuable insights into the disaster chain. It was found that opencast coal mining operations broke the locked segment of the front edge and heavy rainfall softened the slip zones along the faults. Mechanical calculations demonstrated that the coupling condition of the opencast coal mining and heavy rainfall triggered the landslide. A new evolution model was put forth to describe the complex mechanism of combining progressive retreat and tractive failure of hydraulic drive landslide, which was governed by the bedding-plane rock layer. Surface runoff caused the mass of the landslide to liquefy throughout the sliding process, resulting in overlapping deposits, debris-flow-barrier-lake, and erosion. These new insights led to the indication of a different triggering mechanism of landslides-debris flows, as well as laid the foundation for the proposed physical and mechanical mechanism model based on progressive retreat soil-rock mixed landslides with an upper locked segment and lower weak interlayer under heavy rainfall.

Since the 1950's, 212 earth fissures have been discovered in the Wei River Basin. During a field survey in 2016, an additional 48 earth fissures were discovered in Anren area, northeast of the Wei River Basin. The characteristics and formation mechanisms of these fissures were studied through field investigations, measurements, trench excavation, and drilling. On-site investigations indicated that these earth fissures were distributed along a fault-controlled geomorphic boundary. Fissures trended at 60°–80° NE and were divided into five groups. Trenches revealed multiple secondary fissures, exposing severe soil ruptures in the shallow earth surfaces. Drilling profiles revealed that earth fissures dislocated several strata, and resembled synsedimentary faults. Seismic reflection profiles revealed buried faults beneath the earth fissures. The Anren area fissures formed in the following three stages: regional extension that initially generated multiple buried faults; seismic activity rupturing multiple strata, resulting in multiple buried fractures; and finally, erosion processes that propagated the buried fractures to the surface, forming the current earth fissures.

In 2018, Baige, Tibet, witnessed two consecutive large-scale landslides, causing significant damage and drawing widespread attention. From March 2011 to February 2018, the Baige landslide exhibited a 50-m displacement without complete failure, culminating in a collapse in October 2018. The mechanisms behind its resistance to failure despite substantial deformation and the influence of the complex geo-structure within the tectonic mélange belt remain unclear. To address these questions, this study utilized a multidisciplinary approach, integrating on-site geological field mapping, surface deformation monitoring, multielectrode resistivity method, and deep displacement analysis. The aim was to evaluate the impact of the intricate geo-structure within the tectonic mélange belt on the Baige landslide events. Findings reveal that the landslide's geo-structure consists of structurally fractured, mesh-like rock masses, including heterogeneous lenticular rock masses and intermittent brittle shear zones distributed around the lens-shaped rock masses. The study underscores that the inhomogeneous and weakly deformed lenticular rock masses function as natural locked segments, governing the stability of the Baige landslide. Specifically, the relatively intact and hard granodiorite porphyry play a crucial role in locking the landslide's deformation. Deep displacement analysis indicates that the brittle shear zones act as the sliding surfaces. The progressive destruction of the locked segments and the gradual penetration of brittle shear zones, driven by gravitational potential energy, contribute to the landslide occurrence. This research provides critical insights into the formation mechanisms of large-scale landslides within tectonic mélange belts.

In 2018, a catastrophic high-altitude landslide occurred at Baige, located within the tectonic suture zone of the Upper Jinsha River. The failure mechanism of this event remains poorly understood. This study aims to elucidate the deformation characteristics and failure mechanism of the Baige landslide by employing a comprehensive methodology, including field geological surveys, analysis of historical remote sensing imagery, high-density electrical resistivity surveys, and advanced displacement monitoring. Additionally, the physical modeling experiments were conducted to replicate the unique failure modes. The findings propose a novel perspective on the failure mechanism of the Baige landslide, which involves two critical stages: first, the brittle shear zone bypasses and fails at the lower locked segment, and second, the failure of the upper locked segment, combined with the shear zone's impact on the lower locked segment, triggers overall slope instability. Physical modeling experiments revealed a transition from initial acceleration to a rapid acceleration phase, particularly marked by a significant increase in velocity following the failure of the upper locked segment. The intensity of acoustic emission signals was found to correlate with the failure of the locked segments and the state of particle collisions post-failure. It offers new insights into the failure mechanisms of tectonic mélange belt large-scale landslides in suture zones, contributing to the broader field of landslide research.

To map the rock joints in the underground rock mass, a method was proposed to semi-automatically detect the rock joints from borehole imaging logs using a deep learning algorithm. First, 450 images containing rock joints were selected from borehole ZKZ01 in the Rumei hydropower station. These images were labeled to establish ground truth which was subdivided into training, validation, and testing data. Second, the YOLO v2 model with optimal parameter settings was constructed. Third, the training and validation data were used for model training, while the test data was used to generate the precision-recall curve for prediction evaluation. Fourth, the trained model was applied to a new borehole ZKZ02 to verify the feasibility of the model. There were 12 rock joints detected from the selected images in borehole ZKZ02 and four geometric parameters for each rock joint were determined by sinusoidal curve fitting. The average precision of the trained model reached 0.87.

In Southwestern China, the development of karst landforms and planation surfaces is closely related to local tectonics, fluvial incision, and base level changes, and climate changes. However, researches on when these karst landforms and planation surfaces formed and how they evolved along drainage development are scarce. Fortunately, horizontal caves with numerous fluvial deposits in high karst mountains can be served as time markers in landform evolution. Here we select large horizontal caves to perform studies of geomorphology, sedimentology, and geochronology. Fieldwork revealed that more than 25 km long horizontal cave passages are perched 1 500 m higher than the local base level, but filled with several phases of fluvial sediments and breakdown slabs. The first phase of fluvial gravels and related cave drainage was dated back to 6.4 Ma using cosmogenic nuclide burial dating, and the stalagmite covering the cave collapse was dated by the U-Pb method to be older than 1.56 Ma. These results show that the continuous horizontal cave drainage system and the planation surface were developed before the Late Miocene. The lowering process of the base level as a result of the sharp fluvial incision and water level lowering, along with the regional uplift, led to the abandonment of the horizontal cave and the elevated planation surface at the Late Miocene. After that, the phase of cave collapse, thick fluvial sand, and clay sediments in the recharge of cave areas were deposited at around 1.6 Ma and during the Middle Pleistocene, respectively. Subsequently, speleothems were widely deposited on the collapse and clay sediments during the period from 600 to 90 ka, whereas the deposition of cave fluvial sediments terminated suddenly. The tectonic could control the denudation of surface caprocks and the development of karst conduits before the Late Miocene, whereas the river incision acted as the main driver for the base level lowering and the destruction of the horizontal cave drainage at high altitudes. In addition, the rapid incision and retreat of Silurian gorges finally caused the formation of karst mesas in the Middle Pleistocene.

To investigate groundwater flow and solute transport characteristics of the karst trough zone in China, tracer experiments were conducted at two adjacent typical karst groundwater flow systems (Yuquandong (YQD) and Migongquan (MGQ)) in Sixi valley, western Hubei, China. High-resolution continuous monitoring was utilized to obtain breakthrough curves (BTCs), which were then analyzed using the multi-dispersion model (MDM) and the two-region nonequilibrium model (2RNE) with basic parameters calculated by CXTFIT and QTRACER2.Results showed that: (1) YQD flow system had a complex infiltration matrix with overland flow, conduit flow and fracture flow, while the MGQ flow system was dominated by conduit flow with fast flow transport velocity, but also small amount of fracture flow there; (2) They were well fitted based on the MDM (R² = 0.928) and 2RNE (R² = 0.947) models, indicating that they had strong adaptability in the karst trough zone; (3) conceptual models for YQD and MGQ groundwater systems were generalized. In YQD system, the solute was transported via overland flow during intense rainfall, while some infiltrated down into fissures and conduits. In MGQ system, most were directly transported to spring outlet in the fissure-conduit network.

The response of lake environments in arid Central Asia to climate change during the Late Holocene over the centennial to millennial timescales remains contentious. The reason that primarily paleoenvironmental proxies diverse and the scarcity of accurate quantitative reconstruction records. In this study, we employed diatoms and pollen records from lacustrine sediment in the Aibi Lake of Southwest Junggar Basin to quantitatively reconstruct salinity and watershed precipitation amounts while exploring the associated forcing mechanisms. The results indicate that Aibi Lake salinity varied between 2 and 47 g/L during the Late Holocene Period, indicating a generally brackish environment, and corresponding to prevailing Tryblionella granulata diatom in the lake basin. Westerly-dominated annual precipitation varied between 250 and 320 mm during the Late Holocene Period in the basin, exhibiting a generally semi-arid environment and prevailing desert steppe vegetation. The Aibi Lake has a low salinity of average value of ~15 g/L and exhibits elevated precipitation (average value of ~280 mm) during the periods of the 2 900–1 990, 1 570–1140, and 590–120 cal yr BP. The reconstructed precipitation and salinity exhibit a periodicity of ∼200 years, which is consistent with the cycle of phase changes of the North Atlantic oscillation (NAO) and total solar irradiance (TSI). This correlation suggests that variations in NOA and TSI significantly influence the precipitation and salinity changes in Central Asia over centennial to millennial timescales.